A Composite Broad-line Region in SDSS J1609+4902: A Double-peaked Disk Component and a Gaussian Component

The profiles of broad emission lines in active galactic nuclei (AGNs) provide critical insights into the geometry and kinematics of the broad-line region (BLR), which in turn influence the uncertainties in estimating the masses of central supermassive black holes. In this study, we report the discov...

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Main Authors: Jiancheng Wu, Qingwen Wu, Chen Hu, Bing Lyu, Hua-Rui Bai, Yi-Xin Fu, Yu Zhao, Jian-Min Wang, Xinwu Cao
Format: Article
Language:English
Published: IOP Publishing 2025-01-01
Series:The Astrophysical Journal
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Online Access:https://doi.org/10.3847/1538-4357/ade2cc
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author Jiancheng Wu
Qingwen Wu
Chen Hu
Bing Lyu
Hua-Rui Bai
Yi-Xin Fu
Yu Zhao
Jian-Min Wang
Xinwu Cao
author_facet Jiancheng Wu
Qingwen Wu
Chen Hu
Bing Lyu
Hua-Rui Bai
Yi-Xin Fu
Yu Zhao
Jian-Min Wang
Xinwu Cao
author_sort Jiancheng Wu
collection DOAJ
description The profiles of broad emission lines in active galactic nuclei (AGNs) provide critical insights into the geometry and kinematics of the broad-line region (BLR), which in turn influence the uncertainties in estimating the masses of central supermassive black holes. In this study, we report the discovery of a low-luminosity AGN, SDSS J1609+4902, in which the H α line exhibits two distinct BLR components: a Gaussian component and an extremely broad double-peaked component. Follow-up observations conducted at the Lijiang Observatory in 2025 reveal that the line profile remains roughly unchanged, suggesting that this BLR structure may remain stable over a timescale of ∼10 yr. We find that the size of the central Gaussian (full width at half-maximum, FWHM ∼ 3000 km s ^−1 ) component is consistent with the classical reverberation mapping correlation. In contrast, the asymmetric double-peaked wing (FWHM ∼ 23,000 km s ^−1 ) likely originates from a disk-like BLR with an inner radius of approximately 70 gravitational radii. These results provide new constraints on the structure and dynamics of BLRs in AGNs and highlight the potential for long-term stability in such systems.
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spelling doaj-art-deea4d68929c4af38babf5a18db31b022025-08-20T03:30:09ZengIOP PublishingThe Astrophysical Journal1538-43572025-01-0198711410.3847/1538-4357/ade2ccA Composite Broad-line Region in SDSS J1609+4902: A Double-peaked Disk Component and a Gaussian ComponentJiancheng Wu0https://orcid.org/0000-0002-2581-8154Qingwen Wu1https://orcid.org/0000-0003-4773-4987Chen Hu2Bing Lyu3https://orcid.org/0000-0001-8879-368XHua-Rui Bai4Yi-Xin Fu5Yu Zhao6Jian-Min Wang7https://orcid.org/0000-0001-9449-9268Xinwu Cao8https://orcid.org/0000-0002-2355-3498Department of Astronomy, School of Physics, Huazhong University of Science and Technology , Luoyu Road 1037, Wuhan, People’s Republic of ChinaDepartment of Astronomy, School of Physics, Huazhong University of Science and Technology , Luoyu Road 1037, Wuhan, People’s Republic of ChinaKey Laboratory for Particle Astrophysics, Institute of High Energy Physics, Chinese Academy of Sciences , 19B Yuquan Road, Beijing 100049, People’s Republic of ChinaKavli Institute for Astronomy and Astrophysics, Peking University , Beijing 100871, People’s Republic of ChinaKey Laboratory for Particle Astrophysics, Institute of High Energy Physics, Chinese Academy of Sciences , 19B Yuquan Road, Beijing 100049, People’s Republic of ChinaKey Laboratory for Particle Astrophysics, Institute of High Energy Physics, Chinese Academy of Sciences , 19B Yuquan Road, Beijing 100049, People’s Republic of ChinaKey Laboratory for Particle Astrophysics, Institute of High Energy Physics, Chinese Academy of Sciences , 19B Yuquan Road, Beijing 100049, People’s Republic of ChinaKey Laboratory for Particle Astrophysics, Institute of High Energy Physics, Chinese Academy of Sciences , 19B Yuquan Road, Beijing 100049, People’s Republic of ChinaInstitute for Astronomy, School of Physics, Zhejiang University , 866 Yuhangtang Road, Hangzhou 310058, People’s Republic of ChinaThe profiles of broad emission lines in active galactic nuclei (AGNs) provide critical insights into the geometry and kinematics of the broad-line region (BLR), which in turn influence the uncertainties in estimating the masses of central supermassive black holes. In this study, we report the discovery of a low-luminosity AGN, SDSS J1609+4902, in which the H α line exhibits two distinct BLR components: a Gaussian component and an extremely broad double-peaked component. Follow-up observations conducted at the Lijiang Observatory in 2025 reveal that the line profile remains roughly unchanged, suggesting that this BLR structure may remain stable over a timescale of ∼10 yr. We find that the size of the central Gaussian (full width at half-maximum, FWHM ∼ 3000 km s ^−1 ) component is consistent with the classical reverberation mapping correlation. In contrast, the asymmetric double-peaked wing (FWHM ∼ 23,000 km s ^−1 ) likely originates from a disk-like BLR with an inner radius of approximately 70 gravitational radii. These results provide new constraints on the structure and dynamics of BLRs in AGNs and highlight the potential for long-term stability in such systems.https://doi.org/10.3847/1538-4357/ade2ccActive galactic nucleiSupermassive black holesAccretion
spellingShingle Jiancheng Wu
Qingwen Wu
Chen Hu
Bing Lyu
Hua-Rui Bai
Yi-Xin Fu
Yu Zhao
Jian-Min Wang
Xinwu Cao
A Composite Broad-line Region in SDSS J1609+4902: A Double-peaked Disk Component and a Gaussian Component
The Astrophysical Journal
Active galactic nuclei
Supermassive black holes
Accretion
title A Composite Broad-line Region in SDSS J1609+4902: A Double-peaked Disk Component and a Gaussian Component
title_full A Composite Broad-line Region in SDSS J1609+4902: A Double-peaked Disk Component and a Gaussian Component
title_fullStr A Composite Broad-line Region in SDSS J1609+4902: A Double-peaked Disk Component and a Gaussian Component
title_full_unstemmed A Composite Broad-line Region in SDSS J1609+4902: A Double-peaked Disk Component and a Gaussian Component
title_short A Composite Broad-line Region in SDSS J1609+4902: A Double-peaked Disk Component and a Gaussian Component
title_sort composite broad line region in sdss j1609 4902 a double peaked disk component and a gaussian component
topic Active galactic nuclei
Supermassive black holes
Accretion
url https://doi.org/10.3847/1538-4357/ade2cc
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